1. Field of the Invention
The present invention relates to a film-forming composition for optical imprint and a method for producing an optical member.
2. Related Art
Lithographic technologies are core technologies for semiconductor device processes, and along with the high integration of semiconductor integrated circuits (IC's) of recent years, further micronization of wiring is in progress. In particular, in regard to semiconductor integrated circuits (IC's) called ultra-LSIs having a degree of device integration as high as over ten million, microfabrication lithographic technologies are essential.
Here, as the microfabrication lithography technologies for realizing ultra-LSI, optical exposure lithography by means of KrF laser, ArF laser, F2 laser, X rays, far-ultraviolet radiation or the like has been used heretofore. Furthermore, these optical exposure lithography technologies have enabled the formation of patterns in the order of several tens of nanometers (nm).
However, since devices used for the optical exposure lithography techniques are expensive, initial cost for the exposure devices has been increased with the further miniaturization. Moreover, a mask for obtaining a high resolution at the same level as a light wavelength is necessary for the optical exposure lithography, and the mask having such a microshape has been expensive. Furthermore, since the demand for higher integration is limitless, further miniaturization is required.
One of the technologies that have been developed under such circumstances is optical nanoimprint lithography. This is a technology for transferring a pattern onto a resin layer by pressing a mold against a coating layer containing a photocurable resin, subsequently irradiating the resin with ultraviolet radiation to cure the resin, and then separating the mold.
Conventionally, since liquid resin compositions containing an organic solvent are used at the time of forming a coating layer, a process of removing the organic solvent that is included in the coating layer by performing prebaking after application, is considered essential. However, when a resin substrate having excellent moldability is used as a substrate, there is a problem in that prebaking after application degrades the substrate.
Thus, a method has been proposed in which a particular component is incorporated into the resin composition to be applied so that the resin composition will have low viscosity in a solventless state or even when a small amount of an organic solvent is used, and the process of prebaking is not employed (see Patent Document 1). In Patent Document 1, it is considered preferable to adjust the content of the organic solvent to 3% by mass or less relative to the total amount of the composition, and in the Examples a method of mixing the various components of the composition, subsequently stirring the composition at room temperature before it is applied, and volatilizing the organic solvent is employed. Examples of the organic solvent used in this application include ethoxybutanol, isopropanol, methoxypropanol, methyl ethyl ketone, and methyl isobutyl ketone.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2008-202022